Under ordinary circumstances, Montgomery County Executive Isiah Leggett and members of the County Council, progressive Democrats all, would stay away from an event that forced them to cross a picket line. But there’s nothing ordinary about Saturday night.

Organized labor is boycotting the Montgomery County Democratic Central Committee’s annual spring fundraiser, in protest of its support for November’s Question B ballot measure that limited certain kinds collective bargaining for police. It won by a 60-to-40 ratio, upholding a law the council passed unanimously in 2011.

The law eliminated an unusual three-decade-old provision called “effects bargaining,” allowing the Fraternal Order of Police to negotiate certain management decisions because of their potential effect on members. Police officials said the provision, which enabled the FOP to contest such items as placement of video cameras in cruisers or checking e-mail, made it difficult to run the department. The union still retains other basic bargaining rights.

Since the Metropolitan Washington Council AFL-CIO announced the boycott last month, a growing roster of Democrats have announced that they will skip what is known as the Spring Ball. They include Lt. Gov. Anthony G. Brown, who announced his candidacy for governor Friday; a likely primary opponent, Attorney General Douglas F. Gansler; Howard County Executive Ken Ulman; and Del. Heather R. Mizeur, along with most of the rest of Montgomery’s state legislative delegation.

Because it was their law that kindled the dispute, Leggett and the council have little choice but to show up at the Bethesda North Marriott on Saturday. But they’re unhappy — with labor for using the county party’s major annual fundraiser as a venue for protest, and with their fellow elected officials for buckling under union pressure, even though voters (and members of the central committee, by a 109 to 14 vote) made their position clear.

“I’m disappointed,” said council member Phil Andrews (D-Rockville-Gaithersburg), a candidate for county executive in 2014. “The purpose of the Democratic Party is not to say yes to whatever unions ask for, but to what is in the public interest.”

Council member Roger Berliner (D-Potomac-Bethesda) said the boycott is disrespectful to loyal county Democrats. “When 90-plus percent of Democrats [on the central committee] who are sympathetic to labor say, ‘Gee, this is actually the right public policy result,’ that’s about as democratic as you get.”

Joslyn Williams, president of the Metro Washington Council, said in a posting on the organization’s Web site Friday that the issue is not about arcane labor law but “about solidarity, pure and simple.”

“An injury to one is an injury to all,” Williams said, noting that the FOP has supported the AFL-CIO in other recent fights even though it is not a member.

Leggett and seven of nine council members confirmed they would attend Saturday. Council members Nancy Floreen (D-At Large) and Valerie Ervin (D-Silver Spring) said they had scheduling conflicts. Only council member Marc Elrich (D-At Large) said he was undecided.

“I’ve never crossed a picket line in my life. It’s a real issue for me,” he said.

Montgomery Democrats who are skipping the Spring Ball got a scathing e-mail from former Montgomery council member Gail Ewing, who said she was “ashamed” of those observing the boycott.

“This Labor action is despicable — intended to bring the Montgomery County Democratic Central Committee and Party to its knees,” Ewing wrote. “By supporting this boycott our elected officials are saying and affirming that our Democratic Party is just a front for Organized Labor.”